US11008517B2 - Non-perpendicular connections between coke oven uptakes and a hot common tunnel, and associated systems and methods - Google Patents

Abstract

The present technology is generally directed to non-perpendicular connections between coke oven uptakes and a hot common tunnel, and associated systems and methods. In some embodiments, a coking system includes a coke oven and an uptake duct in fluid communication with the coke oven. The uptake duct has an uptake flow vector of exhaust gas from the coke oven. The system also includes a common tunnel in fluid communication with the uptake duct. The common tunnel has a common flow vector and can be configured to transfer the exhaust gas to a venting system. The uptake flow vector and common flow vector can meet at a non-perpendicular interface to improve mixing between the flow vectors and reduce draft loss in the common tunnel.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No. 13/830,971, filed Mar. 14, 2013, which is a continuation-in-part of U.S. patent application Ser. No. 13/730,673, filed Dec. 28, 2012, which are incorporated herein by reference in their entirety. Further, components and features of embodiments disclosed in the application incorporated by reference may be combined with various components and features disclosed and claimed in the present application.

TECHNICAL FIELD

The present technology is generally directed to non-perpendicular connections between coke oven uptakes and a hot common tunnel, and associated systems and methods.

BACKGROUND

Coke is a solid carbonaceous fuel that is derived from coal. Coke is a favored energy source in a variety of useful applications. For example, coke is often used to smelt iron ore during the steelmaking process. As a further example, coke may also be used to heat commercial buildings or power industrial boilers.

In a typical coking process, an amount of coal is baked in a coke oven at temperatures that generally exceed 2,000 degrees Fahrenheit. The baking process transforms the relatively impure coal into coke, which contains relatively few impurities. At the end of the baking process, the coke typically emerges from the coke oven as a substantially intact piece. The coke typically is removed from the coke oven, loaded into one or more train cars, and transported to a quench tower in order to cool or “quench” the coke before it is made available for distribution for use as a fuel source.

The hot exhaust (i.e. flue gas) emitted during baking is extracted from the coke ovens through a network of ducts, intersections, and transitions. The intersections in the flue gas flow path of a coke plant can lead to significant pressure drop losses, poor flow zones (e.g. dead, stagnant, recirculation, separation, etc.), and poor mixing of air and volatile matter. The high pressure drop losses can lead to higher required draft, leaks, and problems with system control. In addition, poor mixing and resulting localized hot spots can lead to earlier structural degradation due to accelerated localized erosion and thermal wear. Erosion includes deterioration due to high velocity flow eating away at material. Hot spots can lead to thermal degradation of material, which can eventually cause thermal/structural failure. The localized erosion and/or hot spots can, in turn, lead to failures at duct intersections.

Traditional duct intersection designs also result in significant pressure drop losses which may limit the number of coke ovens connected together in a single battery. There are limitations on how much draft a draft fan can pull. Pressure drops in duct intersections can take away from the amount of draft available to exhaust flue gases from the coke ovens. These and other related problems with traditional duct intersection design result in additional capital expenses. Therefore, a need exists to provide improved duct intersection/transitions that can improve mixing, flow distribution, minimize poor flow zones, and reduce pressure drop losses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a horizontal heat recovery coke plant, configured in accordance with embodiments of the technology.

FIG. 2 is an isometric, partial cut-away view of a portion of the horizontal heat recovery coke plant ofFIG. 1 configured in accordance with embodiments of the technology.

FIG. 3 is a sectional view of a horizontal heat recovery coke oven configured in accordance with embodiments of the technology.

FIG. 4 is a top view of a portion of a horizontal heat recovery coke plant configured in accordance with embodiments of the technology.

FIG. 5A is a cross-sectional top view of a perpendicular interface between an uptake duct and a common tunnel configured in accordance with embodiments of the technology.

FIG. 5B is a cross-sectional top view of a non-perpendicular interface between an uptake duct and a common tunnel configured in accordance with embodiments of the technology.

FIG. 5C is a cross-sectional end view of a non-perpendicular interface between an uptake duct and a common tunnel configured in accordance with embodiments of the technology.

FIG. 5D is a cross-sectional end view of a non-perpendicular interface between an uptake duct and a common tunnel configured in accordance with embodiments of the technology.

FIG. 5E is a cross-sectional end view of a non-perpendicular interface between an uptake duct and a common tunnel configured in accordance with embodiments of the technology.

FIGS. 6A-6I are top views of various configurations of interfaces between uptake ducts and a common tunnel configured in accordance with embodiments of the technology.

FIG. 7A is a cross-sectional top view of a non-perpendicular interface retrofitted between an uptake and a common tunnel configured in accordance with embodiments of the technology.

FIG. 7B is a cross-sectional top view of an interface between an uptake and a common tunnel configured in accordance with embodiments of the technology.

FIG. 7C is a cross-sectional top view of a non-perpendicular interface retrofitted between the uptake and common tunnel ofFIG. 7B configured in accordance with embodiments of the technology.

FIG. 8 is a cross-sectional top view of a non-perpendicular interface between an uptake and a common tunnel configured in accordance with embodiments of the technology.

FIG. 9 is a plot showing the spatial distribution of gas static pressure along the length of the common tunnel.

DETAILED DESCRIPTION

The present technology is generally directed to non-perpendicular connections between coke oven uptakes and a hot common tunnel, and associated systems and methods. In some embodiments, a coking system includes a coke oven and an uptake duct in fluid communication with the coke oven. The uptake duct has an uptake flow vector of exhaust gas from the coke oven. The system also includes a common tunnel in fluid communication with the uptake duct. The common tunnel has a common flow vector and can be configured to transfer the exhaust gas to a venting system. The uptake flow vector and common flow vector can meet at a non-perpendicular interface to improve mixing between the flow vectors and reduce draft loss in the common tunnel.

Specific details of several embodiments of the technology are described below with reference toFIGS. 1-9. Other details describing well-known structures and systems often associated with coal processing have not been set forth in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments of the technology. Many of the details, dimensions, angles, and other features shown in the Figures are merely illustrative of particular embodiments of the technology. Accordingly, other embodiments can have other details, dimensions, angles, and features without departing from the spirit or scope of the present technology. A person of ordinary skill in the art, therefore, will accordingly understand that the technology may have other embodiments with additional elements, or the technology may have other embodiments without several of the features shown and described below with reference toFIGS. 1-9.

FIG. 1 is a schematic illustration of a horizontal heat recovery (HHR)coke plant100, configured in accordance with embodiments of the technology. TheHHR coke plant100 comprisesovens105, along with heat recovery steam generators (HRSGs)120 and an air quality control system130 (e.g., an exhaust or flue gas desulfurization (FGD) system), both of which are positioned fluidly downstream from theovens105 and both of which are fluidly connected to theovens105 by suitable ducts. TheHHR coke plant100 also includes one or morecommon tunnels110A,110B (collectively “common tunnel110”) fluidly connectingindividual ovens105 to theHRSGs120 via one or moreindividual uptake ducts225. In some embodiments, two ormore uptake ducts225 connect eachindividual oven105 to thecommon tunnel110. Afirst crossover duct290 fluidly connects thecommon tunnel110A to theHRSGs120 and asecond crossover duct295 fluidly connects thecommon tunnel110B to theHRSGs120 atrespective intersections245. Thecommon tunnel110 can further be fluidly connected to one or more bypass exhaust stacks240. A cooledgas duct125 transports the cooled gas from the HRSGs to theFGD system130. Fluidly connected and further downstream are abaghouse135 for collecting particulates, at least onedraft fan140 for controlling air pressure within the system, and amain gas stack145 for exhausting cooled, treated exhaust into the environment.Various coke plants100 can have different proportions ofovens105,HRSGs120,uptake ducts225,common tunnels110, and other structures. For example, in some coke plants, eachoven105 illustrated inFIG. 1 can represent ten actual ovens.

As will be described in further detail below, in several embodiments theuptake ducts225 meet thecommon tunnel110 at non-perpendicular interfaces. The non-perpendicular interfaces may comprise a fitting within theuptake ducts225, a fitting within thecommon tunnel110, anon-perpendicular uptake duct225, a non-perpendicular portion of theuptake duct225, or other feature. The non-perpendicular interfaces can lower the mixing draft loss at the uptake/common tunnel connection by angling the connection in the direction of the common tunnel flow. More specifically, theuptake ducts225 have an uptake flow having an uptake flow vector (having x, y, and z orthogonal components) and thecommon tunnel110 has a common flow having a common flow vector (having x, y, and z orthogonal components). By minimizing the differences between the uptake flow vector and the common flow vector, the lesser the change in the directional momentum of the hot gas and, consequently, the lower the draft losses.

Furthermore, there are interface angles in which the draft in thecommon tunnel110 can increase from the addition of the extra mass flow from theuptake duct225. More specifically, the interface can act as a vacuum aspirator which uses mass flow to pull a vacuum. By aligning theuptake duct225 mass flow with thecommon tunnel110 mass flow (having a velocity vector in the same major flow direction), a coke plant can achieve more vacuum pull and lower draft loss, which can potentially cause a draft increase. The reduced draft loss can be used to reduce thecommon tunnel110 size (e.g., diameter) or lower the required overall system draft.

Further, various embodiments of the technology are not limited to the interface between uptake ducts and the common tunnel. Rather, any connection where the gas flow undergoes a significant change in direction can be improved to have a lower draft loss by using a non-perpendicular connection. For example, any of the connections in the exhaust flow path (e.g., between thecommon tunnel110 and the bypass exhaust stacks240) can include ducts meeting head to head; angling these connections can lower draft losses in the manner described above.

FIGS. 2 and 3 provide further detail regarding the structure and operation of thecoke plant100. More specifically,FIGS. 2 and 3 illustrate further details related to the structure and mechanics of exhaust flow from the ovens to the common tunnel.FIGS. 4 through 9 provide further details regarding various embodiments of non-perpendicular connections between coke oven uptakes ducts and the common tunnel.

FIG. 2 is an isometric, partial cut-away view of a portion of theHHR coke plant100 ofFIG. 1 configured in accordance with embodiments of the technology.FIG. 3 is a sectional view of anHHR coke oven105 configured in accordance with embodiments of the technology. Referring toFIGS. 2 and 3 together, eachoven105 can include an open cavity defined by afloor160, afront door165 forming substantially the entirety of one side of the oven, arear door170 opposite thefront door165 forming substantially the entirety of the side of the oven opposite the front door, twosidewalls175 extending upwardly from thefloor160 intermediate the front165 and rear170 doors, and a crown180 which forms the top surface of the open cavity of anoven chamber185. Controlling air flow and pressure inside theoven chamber185 can be critical to the efficient operation of the coking cycle, and therefore thefront door165 includes one or more primary air inlets190 that allow primary combustion air into theoven chamber185. Each primary air inlet190 includes aprimary air damper195 which can be positioned at any of a number of positions between fully open and fully closed to vary the amount of primary air flow into theoven chamber185. Alternatively, the one or more primary air inlets190 are formed through the crown180.

In operation, volatile gases emitted from the coal positioned inside theoven chamber185 collect in the crown and are drawn downstream in the overall system intodowncomer channels200 formed in one or bothsidewalls175. The downcomer channels fluidly connect theoven chamber185 with asole flue205 positioned beneath theoven floor160. Thesole flue205 forms a circuitous path beneath theoven floor160. Volatile gases emitted from the coal can be combusted in thesole flue205 thereby generating heat to support the carbonization of coal into coke. Thedowncomer channels200 are fluidly connected to chimneys oruptake channels210 formed in one or bothsidewalls175. Asecondary air inlet215 is provided between thesole flue205 and the atmosphere; thesecondary air inlet215 includes asecondary air damper220 that can be positioned at any of a number of positions between fully open and fully closed to vary the amount of secondary air flow into thesole flue205. Theuptake channels210 are fluidly connected to thecommon tunnel110 by the one ormore uptake ducts225. A tertiary air inlet227 is provided between theuptake duct225 and atmosphere. The tertiary air inlet227 includes atertiary air damper229 which can be positioned at any of a number of positions between fully open and fully closed to vary the amount of tertiary air flow into theuptake duct225.

In order to provide the ability to control gas flow through theuptake ducts225 and within theovens105, eachuptake duct225 also includes anuptake damper230. Theuptake damper230 can be positioned at any number of positions between fully open and fully closed to vary the amount of oven draft in theoven105. Theuptake damper230 can comprise any automatic or manually-controlled flow control or orifice blocking device (e.g., any plate, seal, block, etc.). As used herein, “draft” indicates a negative pressure relative to atmosphere. For example, a draft of 0.1 inches of water indicates a pressure of 0.1 inches of water below atmospheric pressure. Inches of water is a non-SI unit for pressure and is conventionally used to describe the draft at various locations in a coke plant. In some embodiments, the draft ranges from about 0.12 to about 0.16 inches of water in theoven105. If a draft is increased or otherwise made larger, the pressure moves further below atmospheric pressure. If a draft is decreased, drops, or is otherwise made smaller or lower, the pressure moves towards atmospheric pressure. By controlling the oven draft with theuptake damper230, the air flow into theoven105 from theair inlets190,215,227 as well as air leaks into theoven105 can be controlled. Typically, as shown inFIG. 3, anindividual oven105 includes twouptake ducts225 and twouptake dampers230, but the use of two uptake ducts and two uptake dampers is not a necessity; a system can be designed to use just one or more than two uptake ducts and two uptake dampers. All of theovens105 are fluidly connected by at least oneuptake duct225 to thecommon tunnel110 which is in turn fluidly connected to eachHRSG120 by thecrossover ducts290,295. The exhaust gases from eachoven105 flow through thecommon tunnel110 to thecrossover ducts290,295.

In operation, coke is produced in theovens105 by first loading coal into theoven chamber185, heating the coal in an oxygen depleted environment, driving off the volatile fraction of coal, and then oxidizing the VM within theoven105 to capture and utilize the heat given off. The coal volatiles are oxidized within the ovens over an extended coking cycle, and release heat to regeneratively drive the carbonization of the coal to coke. The coking cycle begins when thefront door165 is opened and coal is charged onto theoven floor160. The coal on theoven floor160 is known as the coal bed. Heat from the oven (due to the previous coking cycle) starts the carbonization cycle. As discussed above, in some embodiments, no additional fuel other than that produced by the coking process is used. Roughly half of the total heat transfer to the coal bed is radiated down onto the top surface of the coal bed from the luminous flame of the coal bed and the radiant oven crown180. The remaining half of the heat is transferred to the coal bed by conduction from theoven floor160 which is convectively heated from the volatilization of gases in thesole flue205. In this way, a carbonization process “wave” of plastic flow of the coal particles and formation of high strength cohesive coke proceeds from both the top and bottom boundaries of the coal bed.

Typically, eachoven105 is operated at negative pressure so air is drawn into the oven during the reduction process due to the pressure differential between theoven105 and atmosphere. Primary air for combustion is added to theoven chamber185 to partially oxidize the coal volatiles, but the amount of this primary air is controlled so that only a portion of the volatiles released from the coal are combusted in theoven chamber185, thereby releasing only a fraction of their enthalpy of combustion within theoven chamber185. The primary air is introduced into theoven chamber185 above the coal bed through the primary air inlets190 with the amount of primary air controlled by theprimary air dampers195. Theprimary air dampers195 can also be used to maintain the desired operating temperature inside theoven chamber185. The partially combusted gases pass from theoven chamber185 through thedowncomer channels200 into thesole flue205, where secondary air is added to the partially combusted gases. The secondary air is introduced through thesecondary air inlet215. The amount of secondary air that is introduced is controlled by thesecondary air damper220. As the secondary air is introduced, the partially combusted gases are more fully combusted in thesole flue205, thereby extracting the remaining enthalpy of combustion which is conveyed through theoven floor160 to add heat to theoven chamber185. The fully or nearly-fully combusted exhaust gases exit thesole flue205 through theuptake channels210 and then flow into theuptake duct225. Tertiary air is added to the exhaust gases via the tertiary air inlet227, where the amount of tertiary air introduced is controlled by thetertiary air damper229 so that any remaining fraction of uncombusted gases in the exhaust gases are oxidized downstream of the tertiary air inlet227.

At the end of the coking cycle, the coal has coked out and has carbonized to produce coke. The coke is preferably removed from theoven105 through therear door170 utilizing a mechanical extraction system. Finally, the coke is quenched (e.g., wet or dry quenched) and sized before delivery to a user.

FIG. 4 is a top view of a portion of a horizontal heatrecovery coke plant400 configured in accordance with embodiments of the technology. Thecoke plant400 includes several features generally similar to thecoke plant100 described above with reference toFIG. 1. For example, theplant400 includesnumerous uptake ducts425 in fluid communication with coke ovens (not shown) and the hotcommon tunnel110. Theuptake ducts425 can include “corresponding”uptake ducts425a,425bopposite one another on opposing lateral sides of thecommon tunnel110 and a most-upstream or “end”uptake duct425c. Theuptake ducts425 can channel exhaust gas to thecommon tunnel110. The exhaust gas in thecommon tunnel110 moves from an “upstream” end toward a “downstream” end.

In the illustrated embodiments, theuptake ducts425 meet thecommon tunnel110 at a non-perpendicular interface. More specifically, theuptake ducts425 have an upstream angle θ relative to thecommon tunnel110. While the upstream angle θ is shown to be approximately 45°, it can be lesser or greater in other embodiments. Further, as will be discussed in more detail below, in some embodimentsdifferent uptake ducts425 can have different upstream angles θ from one another. For example, there may be a combination of perpendicular (90°) and non-perpendicular (less than 90°) interfaces. The non-perpendicular interfaces between theuptake ducts425 and thecommon tunnel110 can improve flow and reduce draft loss in the manner described above.

FIG. 5A is a cross-sectional top view of a perpendicular interface between anuptake duct525aand thecommon tunnel110 configured in accordance with embodiments of the technology. An uptake flow of exhaust gas in theuptake duct525aintersects a common flow of exhaust gas in thecommon tunnel110 to form a combined flow. Theuptake duct525aand thecommon tunnel110 meet at an interface having an upstream angle α1 and a downstream angle α2 which are each approximately 90°. In other words, using a spherical coordinate system, a direction of the uptake flow vector comprises an azimuthal y-component but no azimuthal x-component, while a direction of the common flow vector and combined flow vector comprises an x-component but no y-component.

FIG. 5B is a cross-sectional top view of a non-perpendicular interface between anuptake duct525band thecommon tunnel110 configured in accordance with embodiments of the technology. The uptake flow from theuptake duct525bintersects the common flow in thecommon tunnel110 to form a combined flow. Theuptake duct525band thecommon tunnel110 meet at an interface having an upstream angle α1 less than 90° and a downstream angle α2 greater than 90°. The non-perpendicular interface thus provides an azimuthal commonality between the uptake flow vector and the common flow vector. In other words, the uptake flow vector comprises an x-component having a direction in common with an x-component of the common flow vector, and the exhaust gas accordingly loses less momentum at theuptake duct525bandcommon tunnel110 interface as compared to the arrangement ofFIG. 5A. The reduced momentum loss can lower the draft loss at the interface or, in some embodiments, can even increase the draft in thecommon tunnel110.

FIG. 5C is a cross-sectional end view of a non-perpendicular interface between anuptake duct525cand acommon tunnel510cconfigured in accordance with embodiments of the technology. While previous embodiments have shown the common tunnel to have a generally circular cross-sectional shape, in the embodiment shown inFIG. 5C thecommon tunnel510chas a generally oval or egg-shaped cross-sectional shape. For example, the common tunnel510 has a height H between a base B and a top T. In some embodiments, the egg-shaped cross-section can be asymmetrical (i.e., top-heavy), such that thecommon tunnel510chas a greater cross-sectional area above a midpoint M between the top T and base B than below the midpoint M. Such a top-heavy design can provide for more room in the upper portion of thecommon tunnel510cfor combustion to occur, as the buoyancy of hot exhaust gas tends to urge combustion upward. The oblong shape of the illustratedcommon tunnel510ccan thus minimize flame impingement along the upper surface of the interior of thecommon tunnel510c. In further embodiments, theuptake duct525ccan comprise any of the circular or non-circular cross-sectional shapes described above with reference to thecommon tunnel510c, and theuptake duct525candcommon tunnel510cneed not have the same cross-sectional shape.

The uptake flow from theuptake duct525cintersects the common flow in thecommon tunnel510cto form a combined flow. Again referencing a spherical coordinate system, theuptake duct525cmeets thecommon tunnel510cat an interface having a negative altitude angle β less than 90° with respect to the horizon (e.g., with respect to the x-y plane). The non-perpendicular interface thus provides an altitudinal difference between the uptake flow vector and the common flow vector. In other words, the uptake flow vector comprises a z-component that differs from a z-component of the common flow vector. In some embodiments, by introducing the uptake flow into the common flow at an altitudinal angle relative to the common flow vector, swirling flow or turbulence is developed inside thecommon tunnel510cto enhance mixing and combustion of unburned volatile matter and oxygen. In other embodiments, the altitude angle β is a positive angle, greater than 90°, or approximately equal to 90°.

Theuptake duct525ccan interface with thecommon tunnel510cat any height between the top T and bottom B of thecommon tunnel510c. For example, in the illustrated embodiment, theuptake duct525cintersects with thecommon tunnel510cin the lower portion of thecommon tunnel510c(i.e., below or substantially below the midpoint M). In further embodiments, theuptake duct525cintersects with thecommon tunnel510cin the upper portion of thecommon tunnel510c, at the midpoint M, at a top T or bottom B of thecommon tunnel510c, or in multiple locations around the cross-sectional circumference of thecommon tunnel510c. For example, in a particular embodiment, one ormore uptake ducts525cmay intersect with thecommon tunnel510cin the lower portion and one or moreother uptake ducts525cmay intersect with thecommon tunnel510cin the upper portion.

FIG. 5D is a cross-sectional end view of a non-perpendicular interface between anuptake duct525dand thecommon tunnel510dconfigured in accordance with embodiments of the technology. In the embodiment shown inFIG. 5D thecommon tunnel510dhas a generally square or rectangular cross-sectional shape. Other embodiments can have other cross-sectional shapes. The uptake flow from theuptake duct525dintersects the common flow in thecommon tunnel510dto form a combined flow. Again referencing a spherical coordinate system, theuptake duct525dand thecommon tunnel510dmeet at an interface having a positive altitude angle β less than 90° with respect to the horizon. In other words, the uptake flow vector comprises a z-component that differs from a z-component of the common flow vector. In some embodiments, by introducing the uptake flow into the common flow at an altitudinal angle different from the common flow, mixing draft loss can be reduced and combustion can be encouraged to occur at a height that does not burn the interior surfaces of thecommon tunnel510d. For example, the downward altitudinal introduction of flow from theuptake duct525dcan counter the buoyancy of the hot exhaust gas to encourage combustion to occur toward the bottom of thecommon tunnel510dso as not to burn the top of the common tunnel501d.

FIG. 5E is a cross-sectional end view of a non-perpendicular interface between an uptake duct525eand acommon tunnel510econfigured in accordance with embodiments of the technology. The interface has several features generally similar to those discussed above with reference toFIGS. 5A-5D. However, in the embodiment illustrated inFIG. 5E, thecommon tunnel510ecomprises a symmetrical, elongated oval. More specifically, thecommon tunnel510eincludes a semi-circular shape at top and bottom positions of thecommon tunnel510e, and generally straight, parallel, elongated sides between the top and bottom semi-circles. The elongated shape can provide several of the advantages described above. For example, the design can provide for more room in the mid-section of thecommon tunnel510efor combustion to occur, as the buoyancy of hot exhaust gas tends to urge combustion upward. Similarly, the downward altitudinal introduction of flow from the uptake duct525eat angle β can further counter the buoyancy of the hot exhaust gas to encourage combustion to occur toward the bottom of thecommon tunnel510e. The oblong shape of the illustratedcommon tunnel510ecan thus minimize flame impingement along the upper surface of the interior of thecommon tunnel510e. In further embodiments, thecommon tunnel510ecan be symmetrical or asymmetrical and have the same or different shapes.

While various features of the uptake duct and common tunnel interface have been shown separately for purposes of illustration, any of these features can be combined to achieve reduced draft loss, combustion control, and the most effective mixing of the uptake flow and common flow. More specifically, the azimuthal angle of interface, the altitudinal angle of interface, the height of interface, the shape of the common tunnel and/or uptake duct, or other feature can be selected to achieve the desired thermal and draft conditions at the interface. Various parameters such as common tunnel draft, desired degree of common tunnel combustion, exhaust gas buoyancy conditions, total pressure, etc. can be some of the considerations in selecting the features of the uptake duct and common tunnel interface.

FIGS. 6A-6I are top views of various configurations of interfaces between uptake ducts and a common tunnel configured in accordance with embodiments of the technology. As will be shown, the uptake ducts can comprise various patterns of perpendicular and non-perpendicular interfaces with the common tunnel, or can comprise various non-perpendicular angles relative to the common tunnel. While the embodiments shown and discussed with reference toFIGS. 6A-6I include numerous features and arrangements, in further embodiments any of these features and/or arrangements can be used independently or in any combination with other features and/or arrangements described herein.

Referring first toFIG. 6A, in some embodiments each of several uptake ducts625ameets thecommon tunnel110 at a less-than-90° upstream angle α. The uptake ducts625athus reduce mixing loss at the combination of common flow and uptake flow in the manner described above. In some embodiments, corresponding (i.e., opposing) uptake ducts625aare laterally offset from one another and are not directly opposing. This is shown in the two most-downstream uptake ducts625ashown inFIG. 6A. In further embodiments, the spacing between individual uptake ducts625a(i.e., along the length of the common tunnel110) can likewise be variable. For example, the distance d between the two most downstream uptake ducts625aalong one side of thecommon tunnel110 is greater than the distance between the other uptake ducts625a. In further embodiments, the spacing is constant between all uptake ducts625a.

FIG. 6B illustrates an embodiment whereuptake ducts625bmeet thecommon tunnel110 at decreasing upstream angles α. For example, at a most downstream position, the uptake ducts may be perpendicular or nearly-perpendicular to thecommon tunnel110. As the uptake tunnels approach an upstream end, the upstream angles α between theuptake ducts625band thecommon tunnel110 become progressively smaller. In some embodiments, the range of upstream angles α varies from about 15° to about 90°. Since the draft pull is weaker farther upstream, this arrangement can progressively reduce the barrier to entry of the uptake flow into the common flow and thereby reduce draft loss due to mixing or stagnant flow regions. In further embodiments, one ormore uptake ducts625bcan be positioned at an upstream angle α that is greater than 90°. In still further embodiments, the trend shown inFIG. 6B can be reversed. More specifically, theuptake ducts625bcan meet thecommon tunnel110 at increasing upstream angles, wherein the most-upstream angle can be near or approaching 90°. Such an arrangement can be useful in embodiments where mixing flow losses are potentially greater at downstream positions having higher accumulated common flow.

FIG. 6C illustrates an embodiment having a combination ofuptake ducts625cmeeting thecommon tunnel110 at non-perpendicular angles α1 and perpendicular angles α2. The illustrated embodiment includes pairs ofnon-perpendicular ducts625calong a side of thecommon tunnel110 followed by pairs ofperpendicular ducts625c, and so on. In further embodiments, there can be more or fewer perpendicular ornon-perpendicular uptake ducts625cin a row.

FIG. 6D illustrates an embodiment having a combination of uptake ducts625dmeeting thecommon tunnel110 at non-perpendicular angles α1 and perpendicular angles α2. The illustrated embodiment includes alternating non-perpendicular ducts625dand perpendicular ducts625dalong a side of thecommon tunnel110.

FIG. 6E illustrates an embodiment having a combination of uptake ducts625emeeting thecommon tunnel110 at non-perpendicular angles αl and perpendicular angles α2. The illustrated embodiment includes individual perpendicular uptake ducts625ealternating with non-perpendicular uptake ducts625e, followed by pairs of non-perpendicular ducts625e, followed by pairs of perpendicular ducts625e, and so on. This pattern or a portion of this pattern can repeat along further sections of thecommon tunnel110. In further embodiments, there can be different combinations of perpendicular and non-perpendicular uptake ducts.

FIG. 6F illustrates an embodiment having a combination ofuptake ducts625fmeeting thecommon tunnel110 at non-perpendicular angles αl and perpendicular angles α2. The illustrated embodiment includes a series ofnon-perpendicular uptake ducts625f, followed by aperpendicular duct625f, followed by another series ofnon-perpendicular ducts625f, and so on.

FIG. 6G illustrates an embodiment having a combination ofuptake ducts625gmeeting thecommon tunnel110 at non-perpendicular angles αl and perpendicular angles α2. The illustrated embodiment includesnon-perpendicular uptake ducts625gon a first lateral side of thecommon tunnel110, andperpendicular ducts625galong a second, opposing, lateral side of thecommon tunnel110.

FIG. 6H illustrates an embodiment having a combination ofuptake ducts625hmeeting thecommon tunnel110 at non-perpendicular angles αl and perpendicular angles α2. The illustrated embodiment includes alternatingnon-perpendicular ducts625handperpendicular ducts625halong a side of thecommon tunnel110, where thenon-perpendicular uptake ducts625hare oppositeperpendicular ducts625hand vice-versa.

FIG. 6I illustrates an embodiment havinguptake ducts625ialong only one lateral side of thecommon tunnel110, with no uptake ducts on the opposing lateral side. In some embodiments, two single-sidedcommon tunnels110 can be operated in a coke plant in a side-by-side parallel arrangement. Theuptake ducts625ican be angled at non-perpendicular angle α relative to thecommon tunnel110 in the manner described above.

FIG. 7A is a cross-sectional top view of a non-perpendicular interface retrofitted between aperpendicular uptake duct725aand thecommon tunnel110 configured in accordance with embodiments of the technology. Theuptake duct725aand thecommon tunnel110 can originally have the same arrangement as the embodiment discussed above with reference toFIG. 5A, but can be retrofitted to include one or more non-perpendicular interface features. For example, the interface has been fitted with an internal baffle726ato alter the flow pattern and create a non-perpendicular interface. More specifically, the baffle726ais placed in a lumen of theuptake duct725aand modifies a perpendicular interface into an angled interface that reduces draft loss due to mixing. In the illustrated embodiment, the baffle726ais triangle-shaped and converges the uptake flow by reducing an inner characteristic dimension of theuptake duct725a. This converged flow can act as a nozzle and minimize flow energy losses of the uptake flow and/or common flow. In further embodiments, the baffle726acan be adjustable (i.e., movable to adjust the flow and interface pattern), can have different shapes and/or sizes, and/or can converge and/or diverge flow to other degrees. Further, the baffle can extend around more or less of the lumen of theuptake duct725a.

Thecommon tunnel110 can further be retrofitted with aflow modifier703 positioned on an interior surface of thecommon tunnel110 and configured to interrupt or otherwise modify flow in thecommon tunnel110, or improve the interface (i.e., reduce draft loss) at the junction of the uptake flow and the common flow. Theuptake duct725ahas further been modified with a bumped-out diverging flow plate D. The diverging flow plate D modifies the uptake flow vector to have an x-component in common with a common flow vector, thus reducing draft loss between the uptake flow and the common flow. While the diverging flow plate D, the baffle726a, and theflow modifier703 are shown in use together, in further embodiments, any of these features can be used independently or in any combination with any other features described herein.

While the terms “baffle”726aand “flow modifier”703 are used herein, the additions to the uptake duct726aorcommon tunnel110 can comprise any insulation material, refractory material, or other thermally-suitable material. In some embodiments, theflow modifier703 and/or baffle726amay comprise a single or multilayer lining that is built up with a relatively inexpensive material and covered with a skin. In yet another embodiment, refractory or similar material can be shaped via gunning (i.e. spraying). Better control of shaping via gunning may be accomplished by gunning in small increments or layers. In addition, a template or mold may be used to aid the shaping via gunning. A template, mold, or advanced cutting techniques may be used to shape the refractory (e.g. even in the absence of gunning for the main shape of an internal insert) for insertion into the duct and then attached via gunning to the inner lining of the duct. In yet another embodiment, theflow modifier703 and/or baffle726amay be integrally formed along the duct. In other words, theuptake duct725awall may be formed or “dented” to provide a convex surface along the interior surface of the duct. As used herein, the term convex does not require a continuous smooth surface, although a smooth surface may be desirable. For example, theflow modifier703 and/or baffle726amay be in the form of a multi-faceted protrusion extending into the flow path. Such a protrusion may be comprised of multiple discontinuous panels and/or surfaces. Furthermore, theflow modifier703 and/or baffle726aare not limited to convex surfaces. The contours of theflow modifier703 and/or baffle726amay have other complex surfaces, and can be determined by design considerations such as cost, space, operating conditions, etc. In further embodiments, there can be more than oneflow modifier703 and/or baffle726a. Further, while theflow modifier703 is shown in thecommon tunnel110, in further embodiments theflow modifier703 can be positioned at other locations (e.g., entirely or partially extending into theuptake duct725a, or around the inner circumference of thecommon tunnel110.

FIG. 7B is a cross-sectional top view of an interface between anuptake duct725band acommon tunnel110 configured in accordance with embodiments of the technology.FIG. 7C is a cross-sectional top view of a non-perpendicular interface retrofitted between theuptake duct725bandcommon tunnel110 ofFIG. 7B. Referring toFIGS. 7B and 7C together, theuptake duct725bincludes a diverging uptake end D that flares at the interface with thecommon tunnel110. Theuptake duct725bcan be retrofitted with aninternal baffle726cgenerally similar to the internal baffle726adescribed above with reference toFIG. 7A. Theinternal baffle726cofFIG. 7C can eliminate the flare or a portion of the flare at the diverging end D, to create a non-perpendicular interface between theuptake duct725band thecommon tunnel110 to reduce draft loss. In further embodiments, the entire internal circumference of theuptake duct725bcan be fitted with thebaffle726cto further narrow or otherwise alter the interface. Thebaffle726ccan minimize flow energy losses as the uptake flow meets the common flow in thecommon tunnel110.

FIG. 8 is a cross-sectional top view of a non-perpendicular interface between anuptake duct825 and thecommon tunnel110 configured in accordance with embodiments of the technology. Theuptake duct825 includes a converging portion C followed by a diverging portion D. The converging portion C can minimize flow energy losses as the exhaust gas from theuptake duct825 meets the common flow in thecommon tunnel110. The diverging portion provides an interface that modifies the uptake flow vector to have an x-component in common with a common flow vector, thus reducing draft loss between the pressurized uptake flow and the common flow. In various embodiments, the diverging and converging portions can have smooth or sharp transitions, and there can be more or fewer converging or diverging nozzles in theuptake duct825 orcommon tunnel110. In another embodiment, the converging portion C is adjacent to thecommon tunnel110 and the diverging portion D is upstream in theuptake duct825. In further embodiments, the converging portion C can be used independently from the diverging portion D, and vice versa.

The interface ofFIG. 8 further includes ajet803 configured to introduce a pressurized fluid such as air, exhaust gas, water, steam, fuel, oxidizer, inert, or other fluid (or combination of fluids) to the uptake flow or common flow as a way to improve flow and reduce draft loss. The fluid can be gaseous, liquid, or multiphase. Thejet803 can stem from or be supported by any external or internal pressurized source (e.g., a pressurized vessel, a pressurized line, a compressor, a chemical reaction or burning within the coking oven system that supports energy to create pressure, etc.). While thejet803 is shown as penetrating thecommon tunnel110 at a position downstream of theuptake duct825, in further embodiments thejet803 can be positioned in theuptake duct825, upstream of theuptake duct825 in thecommon tunnel110, in multiple locations (e.g., a ring) around the circumference of thecommon tunnel110 or uptake duct825a, a combination of these positions, or other positions. In a particular embodiment, thejet803 can be positioned in theuptake duct825 upstream of the converging portion C. Thejet803 can act as an ejector, and can pull a vacuum draft behind the pressurized fluid. Thejet803 can thus modify flow to create improved draft conditions, energize flow or mixing, or can reduce stagnant air or “dead” zones. In various embodiments, thejet803 can pulse the fluid, provide constant fluid, or be run on a timer. Further, thejet803 can be controlled manually, in response to conditions in thecommon tunnel110,uptake duct825, or other portion of the exhaust system, or as part of an advanced control regime. While thejet803 is shown in use with theparticular uptake duct825 arrangement illustrated inFIG. 8, in further embodiments, thejet803 anduptake duct825 could be employed independently or in any combination with any other features described herein. For example, in a particular embodiment, thejet803 could be used in combination with theflow modifier703 shown inFIG. 7A, and could be proximate to or protrude through such aflow modifier703.

FIG. 9 is a plot showing the spatial distribution of the difference in static pressure (in inches-water) along the length of the common tunnel. In other words, the plot illustrates the difference in static pressure at downstream positions in the common tunnel compared to the static pressure at the upstream end. As shown in the plot, the 45 degree uptake has a much lower draft loss over the same length of common tunnel as compared to the perpendicular uptake. This is because the angled uptake has less mixing loss than the perpendicular uptake.

EXAMPLES

The following Examples are illustrative of several embodiments of the present technology.

1. A coking system, comprising:

• • a coke oven;
  • an uptake duct in fluid communication with the coke oven and having an uptake flow vector of exhaust gas from the coke oven; and
  • a common tunnel in fluid communication with the uptake duct, the common tunnel having a common flow vector of exhaust gas and configured to transfer the exhaust gas to a venting system, wherein the uptake flow vector and common flow vector meet at a non-perpendicular interface.

2. The coking system of example 1 wherein at least a portion of the uptake duct is non-perpendicular to the common tunnel.

3. The coking system of example 1 wherein the non-perpendicular interface comprises at least one of an altitudinal difference or an azimuthal commonality between the uptake flow vector and the common flow vector.

4. The coking system of example 1 wherein the common tunnel has a common tunnel height, an upper portion above a midpoint of the common tunnel height, and a lower portion below the midpoint of the common tunnel height, and wherein the uptake duct interfaces with the common tunnel in at least one of the upper portion and the lower portion.

5. The coking system of example 1 wherein the non-perpendicular interface comprises at least one of a baffle, gunned surface, contoured duct liner, or convex flow modifier inside at least one of the uptake duct or common tunnel and configured to alter at least one of the uptake flow vector or common flow vector.

6. The coking system of example 5 wherein the baffle, gunned surface, contoured duct liner, or convex flow modifier is integral to at least one of the uptake duct or common tunnel or is retrofitted onto the uptake duct or common tunnel.

7. The coking system of example 1 wherein at least one of the uptake duct or the interface comprises a converging or diverging pathway.

8. The coking system of example 1 wherein the uptake duct comprises a first uptake duct in fluid communication with a first coke oven and having a first uptake flow vector, and wherein the system further comprises a second uptake duct in fluid communication with the first coke oven or a second coke oven and having a second uptake flow vector of exhaust gas.

9. The coking system of example 8 wherein the first uptake flow vector and common flow vector meet at a non-perpendicular interface, and the second uptake flow vector and common flow vector meet at a perpendicular interface.

10. The coking system of example 8 wherein the first uptake flow vector and common flow vector meet at a non-perpendicular interface and the second uptake flow vector and common flow vector meet at a non-perpendicular interface.

11. The coking system of example 8 wherein at least a portion of the first uptake duct is non-perpendicular to the common tunnel by a first angle and at least a portion of the second uptake duct is non-perpendicular to the common tunnel by a second angle different from the first angle.

12. The coking system of example 8 wherein:

• • the system further comprises a third uptake duct in fluid communication with the first coke oven, the second coke oven, or a third coke oven and having a third uptake flow vector of exhaust gas;
  • the first uptake duct, second uptake duct, and third uptake duct are positioned along a lateral side of the common tunnel; and
  • there is a first distance between the first uptake duct and second uptake duct and a second distance different from the first distance between the second uptake duct and the third uptake duct.

13. The coking system of example 8 wherein the first uptake duct is positioned on a first lateral side of the common tunnel and the second uptake duct is positioned on a second lateral side of the common tunnel opposite the first lateral side, and wherein the first uptake duct and second uptake duct are laterally offset from one another.

14. The coking system of example 8 wherein the first uptake duct and second uptake duct are positioned on a common lateral side of the common tunnel, and wherein there are no uptake ducts on an opposing lateral side of the common tunnel.

15. The coking system of example 1 wherein the common tunnel has one of a circular, non-circular, oval, elongated oval, asymmetrical oval, or rectangular cross-sectional shape.

16. A method of reducing draft losses in a common tunnel in a coking system, the method comprising:

• • flowing exhaust gas from a coke oven through an uptake duct;
  • biasing the exhaust gas exiting the uptake duct toward a common flow in the common tunnel; and
  • merging the exhaust gas and common flow at a non-perpendicular interface.

17. The method of example 16, further comprising at least one of converging or diverging the exhaust gas in or upon exiting the uptake duct.

18. The method of example 16 wherein biasing the exhaust gas comprises biasing the exhaust gas with a baffle in the uptake duct.

19. The method of example 16, further comprising increasing a draft in the common tunnel upon merging the exhaust gas and common flow.

20. The method of example 16 wherein biasing the exhaust gas comprises biasing the exhaust gas within the uptake duct, wherein the uptake duct is at least partially non-perpendicular to the common tunnel.

21. The method of example 16, further comprising introducing a pressurized fluid via a jet into at least one of the uptake duct or the common tunnel.

22. A coking system, comprising:

• • a common tunnel configured to direct a gas from one or more coke ovens to a common stack, wherein the common tunnel has a common tunnel flow with a common tunnel flow vector, and wherein the common tunnel flow vector has an x-component and a y-component;
  • a coke oven in fluid connection with the common tunnel via an uptake, wherein—
    • the uptake connects to the common tunnel at an intersection, and
    • the uptake includes an uptake flow having an uptake flow vector with an x-component and a y-component; and
  • wherein the uptake flow vector x-component has a same direction as the x-component of the common tunnel flow vector.

23. The coking system of example 22 wherein an inner characteristic dimension of the uptake at least one of increases or decreases in the direction of the intersection.

24. The coking system of example 22 wherein the uptake further includes an angled baffle at or near the intersection, the baffle configured to redirect the uptake flow.

Traditional heat recovery coke ovens employ an uptake duct connection from the coke oven to the hot common tunnel that is perpendicular to the common tunnel. Due to the perpendicular shape of the interface, the hot flue gas moving toward the common tunnel experiences a 90-degree change in flow direction. This induces considerable flow losses which can lead to a higher pressure drop. Such mixing losses are undesirable. In order to maintain the system under negative pressure, the high draft loss may require that either the common tunnel be made larger or a higher draft be pulled on the whole system to off-set this higher draft loss.

The non-perpendicular interfaces disclosed herein can lower the mixing draft loss at the uptake/common tunnel connection by angling the connection in the direction of the common tunnel flow. The smaller the upstream angle between the uptake duct and the common tunnel, the lesser the change in the directional momentum of the hot gas and, consequently, the lower the draft losses. By using non-perpendicular interfaces and aligning the uptake duct flow in the direction of the common tunnel flow, the draft loss can be lowered, which then can be used to reduce the common tunnel size or lower the required draft. For example, in some embodiments, the technology described herein can reduce the common tunnel insider diameter to 7-9 feet. The technology could similarly allow a longer common tunnel that would traditionally have been prohibitive due to draft losses. For example, in some embodiments, the common tunnel can be long enough to support 30, 45, 60, or more ovens per side.

From the foregoing it will be appreciated that, although specific embodiments of the technology have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the technology. Further, certain aspects of the new technology described in the context of particular embodiments may be combined or eliminated in other embodiments. Moreover, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein. Thus, the disclosure is not limited except as by the appended claims.

Claims (5)

We claim:

1. A coking system, comprising:

a common tunnel configured to direct a gas from one or more coke ovens to a common stack, wherein the common tunnel has a common tunnel flow with a common tunnel flow vector, and wherein the common tunnel flow vector, on a spherical coordinate system having an x-axis, y-axis, and z-axis, has an x-component extending along a long axis of the common tunnel, a y-component extending along a width of the common tunnel, and a z-component extending along a height of the common tunnel;

a coke oven in fluid connection with the common tunnel via an uptake, wherein:

the uptake connects to the common tunnel at an intersection;

the uptake includes an uptake flow having an uptake flow vector, at the intersection, with an x-component, a y-component, and a z-component on the spherical coordinate system; and

wherein the uptake is disposed at an angle with respect to the common tunnel, at the intersection, such that the uptake flow vector x-component has a direction in common with of the common flow vector x-component but the uptake flow vector z-component differs from the z-component of the common tunnel flow vector, thereby encouraging mixing and combustion of unburned volatile material and oxygen inside the common tunnel.

2. The coking system ofclaim 1 wherein an inner characteristic dimension of the uptake at least one of increases or decreases in the direction of the intersection.

3. The coking system ofclaim 1 wherein the uptake further includes an angled baffle at or near the intersection, the baffle configured to redirect the uptake flow.

4. The coking system ofclaim 1 wherein the common tunnel has an elliptical cross-sectional shape.

5. The coking system ofclaim 1 wherein the z-component of the uptake flow vector is in a downward direction, such that buoyancy of gases exiting the uptake are at least partially countered and combustion of the gases is encouraged to occur toward a lower portion of the common tunnel.

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